The effect of mould temperature and cooling conditions on the size of secondary dendrite arm spacing in Al-7Si-3Cu alloy

Abstract

The secondary dendrite arm spacing (SDAS) is one of the most important microstructure features of as-cast structure in hypoeutectic aluminum alloys. The size of SDAS depends on many factors such as liquid metal treatment, temperature gradient, cooling rate/solidification time and chemical composition of melt. Among them the cooling rate/solidification time have dominant impacts. In industrial production of castings, when the chemical composition of melt has been chosen, the cooling conditions will control the solidification process. In this paper the effect of various pre-heating mould temperatures and cooling conditions (with and without water cooling) on the SDAS in AlSi7Cu3 were studied. For that purpose the permanent metal mould with the cooling system incorporated in one die was designed. The solidification time was affected by the mould temperature. It was found that the influence of mould temperature on SDAS was less pronounced in the presence of water cooling. The experimental results concerning the value of SDAS were compared with calculated value of SDAS obtained as a result of solidification process simulated by WinCast FEM Software.